The Portuguese began the practice, in Arguin in the l440s, of the carimbo, the branding of a slave with a hot iron, leaving a mark in red on the shoulder, the breast, or the upper arm, so that it was evident that he or she was the property of the king of Portugal, or some other master, and that a proper duty had been paid. This procedure survived from the Middle Ages --- indeed, from antiquity: the Romans used to brand their slaves but, when Constantine the Great ruled that slaves condemned to work in mines or fight in the arena were to be marked on the hands or legs, not the face, many slave owners substituted bronze collars for branding.

Each European nation during the slaving centuries had its special procedures. Thus slaves landed at São Tome were branded with a cross on the right arm in the early sixteenth century; but, later, this design was changed to a "G," the marca de Guiné. Slaves exported from Luanda were often branded not once but twice, for they had to receive the mark of the Luso-Brazilian merchants who owned them as well as the royal arms --- on the right breast --- to signify their relation to the Crown. Sometimes, baptism led to the further branding of a cross over the royal design. Slaves of the Royal Africa Company were marked, with a burning iron upon the right breast, "DY," duke of York, after the chairman of the company. In the late eighteenth century, a "G" would indicate that the slave concerned had been marked by the Compañía Gaditana, the Cádiz company concerned to import slaves into Havana in the late 1760s. Captain Thomas Phillips, an interloper, described how

we mark'd the slaves [whom] we had bought on the breast or shoulder with a hot iron, having the ship's name on it, the place being before anointed with a little palm oil, which caused but little pain, the mark being usually well in four or five days.

The South Sea Company later branded its slaves with the distinctive mark of the port in the Spanish empire to which they were being shipped --- Cartagena, Caracas, Veracruz, and so on --- this new brand being made of gold or silver: preferably the latter, because "it made a sharper scar." That enterprise's Court of Directors in London in 1725 specified that the slaves should be marked on the

left shoulder, heating the mark red hot and rubbing the part first with a little palm or other oil and taking off the mark pretty quick, and rubbing the place again with oil.

Willem Bosman reported of his Dutch colleagues and himself, "We take all possible care that they are not burned too hard, especially the women, who are more tender than the men." A Dutch instruction of the late eighteenth century, to the Middelburgische Kamerse Compagnie, was more specific: it insisted that,

as you purchase slaves, you must mark them at the upper right arm with the silver mark CCN...the area of marking must first be rubbed with candle wax or oil; the marker should only be as hot as when applied to paper the paper gets hot....

The French had a similar technique:

After discussion, the captain inscribes on a slate the merchandise for exchange, a specific officer delivers, while the bought African waits in a prison before being attached to a ring and taken to the canoe which will carry him to the ship. The surgeon stamps the slave on the right shoulder with an iron which gives him the mark of the shippers and the ship --- it will never come off (if the slave is of second rank, he is stamped on the right thigh).

In the eighteenth century, sometimes the initials of the shipper were marked, "une pipe sous le téton gauche."

A German surgeon who traveled with the Brandenburg Company's slave ship the Friedrich Wilhelm in 1693 gave one of the most vivid descriptions. He discussed carrying out his duties in Whydah: As soon as a sufficient number of the unfortunate victims were assembled,wrote Dr. Oettinger, who was from Swabia,

they were examined by me. The healthy and strong ones were bought, while the magrones [the word was from the Portuguese magro, "weak"] --- those who had fingers or teeth missing, or were disabled --- were rejected. The slaves who had been bought then had to kneel down, twenty or thirty at a time; their right shoulder was smeared with palm oil and branded with an iron which bore the initials CABC [Churfürstlich Afrikanisch Brandenburg Compagnie]....Some of these poor people obeyed their leaders without a will of their own or any resistance....Others on the other hand howled and danced. There were... many women who filled the air with heartrending cries which could hardly be drowned by the drums, and cut me to the quick.

Pieter de Marees in 1600 reported that the Africans also branded their slaves.

By the eighteenth century, the Portuguese forbade the embarkment of any slave who had not been baptized. That had not always been so: most of the slaves taken to Portugal in the fifteenth century were not christened. That did not hinder some slaves from being received into the church afterwards, a consummation which in turn did not prevent their remaining slaves --- even if the enslavement of a Christian had been condemned by Pope Pius II. But King Manuel the Fortunate, in the early sixteenth century, ordered all masters in Portugal to baptize their slaves, on pain of losing them --- unless the slaves themselves did not want it (as was the case with the small number of Muslim slaves, mostly by then brought from West Africa). All slave children in Portugal were to be christened, whatever happened. King Manuel made it possible for black slaves in Portugal to be able to receive the sacrament from the hands of the priest of the Nossa Senhora da Conceiçãio, a church in Lisbon destroyed in the earthquake of 1755. Captains of ships could baptize slaves about to die on board their ships. This procedure was regularized by Pope Leo X, at the beginning of his pontificate, in a bull of August 1513, Eximiæ Devotionis; he also asked for a font to be built in Nossa Senhora da Conceiçãio for the baptism of slaves.

In the early seventeenth century, it became customary for slaves in Africa to be baptized before their departure from Africa. This requirement was first laid down by King Philip III of Spain (II of Portugal) in 1607 and confirmed in 1619. The slaves had, as a rule, received no instruction whatever before this ceremony, and many, perhaps most, of them had no previous indication that there was such a thing as a Christian God. So the christening was perfunctory. In Luanda, the captives would be taken to one of the six churches, or assembled in the main square. An official catechist, a slave, say, who spoke Kimbundu, the language of Luanda, would address the slaves on the nature of their Christian transformation. Then a priest would pass among the bewildered ranks, giving to each one a Christian name, which had earlier been written on a piece of paper. He would also sprinkle salt on the tongues of the slaves, and follow that with holy water. Finally, he might say, through an interpreter:

Consider that you are now children of Christ. You are going to set off for Portuguese territory, where you will learn matters of the Faith. Never think any more of your place of origin. Do not eat dogs, nor rats, nor horses. Be content.